Cooling system for machine having radiator assembly and method

ABSTRACT

A cooling system for a machine includes a radiator assembly having a tank access port, and an overflow port formed in a radiator tank. A solid cap is coupled with the radiator tank to seal the tank access port, and a valve mechanism is coupled with the radiator tank. The valve mechanism includes a pressure relief valve and a coolant return valve operable to fluidly connect the radiator tank with a recovery bottle responsive to a pressurized or a vacuum state of the radiator tank, respectively.

TECHNICAL FIELD

The present disclosure relates generally to a cooling system for a machine, and more particularly to a cooling system separating functions of coolant pressure relief and recovery from radiator capping.

BACKGROUND

Cooling systems are used across virtually all fields of modern machinery. In one known application, a cooling system equipped with one or more liquid-to-air heat exchangers is provided for cooling an internal combustion engine. A pump driven from the engine gear train circulates coolant between the engine block and a heat exchanger in the nature of an air-cooled radiator. The circulated coolant exchanges heat with material of the engine block, and rejects the heat to ambient air conveyed across exterior surfaces of the radiator in a well-known manner. It is common for such cooling systems to include one or both of an engine oil cooler and a transmission fluid cooler each of which transfers heat into the circulated coolant. A great many different configurations and combinations of cooling system components have been produced for more than a century. Outside of the context of engine systems, cooling systems for machinery are used to cool pumps, compressors, electric motors, milling and cutting tools, and all manner of industrial and commercial equipment.

One feature common to most liquid cooling systems for machinery is the use of a liquid coolant that changes in volume relatively substantially with changes in temperature. It is well known that an engine coolant, such as glycol, water, mixtures of glycol and water, and other materials can increase in temperature sufficiently to increase volume of the coolant greater than a closed volume of the cooling system. So-called “recovery bottles” are commonly used in conjunction with radiators to accommodate the increased volume of coolant produced in response to an increase in temperature, and store the coolant for eventual return into the system as temperatures decrease.

A fluid pressure of coolant is commonly raised apace with increases in temperature. As temperatures decrease the fluid pressure of course decreases along with it. The up-and-down pressure cycling produced by increases and decreases in coolant volume can result in coolant being pushed out of a radiator and sucked back into the radiator many times during the course of a typical cooling system duty cycle. This near-constant change in pressure and temperature and in-and-out flow of fluid can make certain components of the cooling system susceptible not only to thermal and/or structural fatigue, but also to seal failure.

It is necessary to provide relatively robust sealing in the plumbing that connects all parts of the cooling system, and in particular between the radiator and the recovery bottle. A typical design employs a radiator cap having integrated valve structures that enable pressure relief to flow coolant to a recovery bottle, and return when appropriate. U.S. Pat. No. 4,167,159 to Warman is directed to a pressurized liquid cooling system for an internal combustion engine, and discloses a radiator cap of generally conventional design that provides fluid paths for expansion and contraction of coolant. As described in Warman, the pressure cap has pressure and vacuum relief valve components for limiting the maximum operating pressure of the system and for limiting negative pressures to avoid damage during cooling after engine shutdown. A lower system relief pressure for lower-temperature conditions is provided by way of a second, temperature-responsive, pressure relief valve. While Warman perhaps provides advantages in some applications, certain of the components are still likely susceptible to leakage or other problems.

SUMMARY OF THE INVENTION

In one aspect, a cooling system for a machine includes a radiator assembly including a radiator tank having formed therein a tank access port, an overflow port, and a plurality of coolant circulation ports, for connecting with a coolant circulation loop. The radiator assembly further includes a cap coupled with the radiator tank to seal the tank access port, and a valve mechanism. The valve mechanism includes a valve body coupled with the radiator tank and having formed therein an inlet fluidly connected with the overflow port, and an outlet structured to fluidly connect with a recovery bottle. The valve mechanism further includes a pressure relief valve positioned fluidly between the inlet and the outlet and having a first valve opening surface, and a coolant return valve positioned fluidly between the inlet and the outlet and having a second valve opening surface. The first valve opening surface is exposed to a fluid pressure of the inlet, such that the pressure relief valve opens in response to a pressure drop from the inlet to the outlet, to convey coolant from the radiator to the recovery bottle. The second valve opening surface is exposed to a fluid pressure of the outlet such that the coolant return valve opens in response to a pressure drop from the outlet to the inlet, to convey coolant from the recovery bottle to the radiator.

In another aspect, a radiator assembly includes a radiator tank having an inner surface defining an internal fluid space, and an outer surface, and having formed therein a plurality of coolant circulation ports, a tank access port, and an overflow port. The assembly further includes a cap coupled with the radiator tank at the tank access port and blocking fluid flow through the tank access port, and a valve mechanism coupled with the radiator tank at the overflow port. The valve mechanism includes a valve body having formed therein an inlet fluidly connecting with the overflow port, and an outlet structured to fluidly connect with the recovery bottle. The valve mechanism further includes a pressure relief valve having a first valve opening surface, and a coolant return valve having a second valve opening surface. The valve mechanism is in a first state where the first valve opening surface is exposed to a fluid pressure of the inlet and the second valve opening surface is exposed to a fluid pressure of the outlet and the valve mechanism blocks fluid flow through the overflow port. The valve mechanism is adjustable to a second state to permit fluid flow through the overflow port by way of opening the pressure relief valve responsive to a pressure drop from the inlet to the outlet or to a third state to permit fluid flow through the overflow port by way of opening the coolant return valve in response to a pressure drop from the outlet to the inlet.

In still another aspect, a method of operating a cooling system for a machine includes conveying a coolant between a radiator and a coolant circulation loop structured to exchange heat with a machine, and increasing a temperature and a pressure of the coolant within the cooling system by way of the exchange of heat. The method further includes opening a pressure relief valve in a valve mechanism coupled to the radiator at an overflow port in response to the increase in pressure, and venting an excess volume of the coolant produced in response to the increase in temperature to a recovery bottle by way of the pressure relief valve. The method further includes decreasing the temperature in the pressure of the coolant such that a volume of the coolant is reduced, and opening a coolant return valve in the valve mechanism in response to the decrease in pressure. The method still further includes returning coolant to the radiator by way of the coolant return valve, and inhibiting leakage of coolant and air through a tank access port during the venting of the excess volume of coolant and the returning of the coolant to the radiator by way of a solid cap fluidly sealing the tank access port.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side diagrammatic view of a machine system including a cooling system, according to one embodiment;

FIG. 2 is a side diagrammatic view of a machine system having a cooling system, according to another embodiment;

FIG. 3 is a partially sectioned side diagrammatic view of a portion of the cooling system shown in FIG. 1; and

FIG. 4 is a partially sectioned side diagrammatic view of a portion of a cooling system according to another embodiment.

DETAILED DESCRIPTION

Referring to FIG. 1, there is shown a cooling system 10 for a machine 12, according to one embodiment. Cooling system 10 may be of a type suitable for use in cooling an internal combustion engine, thus machine 12 may include an engine. The present disclosure is not thereby limited, however, and other cooling applications are contemplated such as industrial and manufacturing applications, mining equipment applications, and still others. In a practical implantation strategy, cooling system 10 includes a radiator assembly 14 including a radiator tank 16 that includes a tank wall 18, having formed therein a tank access port 24, an overflow port 26, and a plurality of coolant circulation ports 28 and 30, for connecting with a coolant circulation loop 32. Radiator assembly 14 further includes a cap 46 coupled with radiator tank 16 to seal tank access port 24, and a valve mechanism 48 that includes a valve body 50 coupled with radiator tank 16. As will be further apparent from the following description valve mechanism 48 may be structured to provide for pressure relief and coolant return as coolant in cooling system 10 changes in temperature and volume.

Referring also now to FIG. 3, there is shown an outer surface 20 and an inner surface 22 of tank wall 18, with inner surface 22 defining an internal fluid space 60 for containing a suitable liquid coolant such as a glycol-based coolant. Radiator tank 16 defines a vertical axis 100, and in a practical implementation strategy may be structured with a plurality of flow-through channels (not shown) such that cooling air from a radiator fan or the like can be pushed through radiator tank 16 in generally horizontal directions towards machine 12 or away from machine 12. Radiator tank 16 may further include a plurality of internal cooling structures, such as turbulators, not shown in the attached illustrations. Radiator tank 16 may be structured such that tank wall 18 is formed from an extrusion, such as an aluminum extrusion, with adjoining sections of wall being connected by and supported by fillet structures or the like, such as the fillet 19 shown in FIG. 3.

Cooling system 10 may further include a recovery bottle 34 having a bottle inlet 35, and a vent line 36 fluidly connecting valve mechanism 48 to recovery bottle 34. Valve mechanism 48, more particularly valve body 50, may have formed therein an inlet 52 fluidly connected with overflow port 26, and an outlet 54 structured to fluidly connect with recovery bottle 34. Cooling system 10 may further include a thermostat assembly 38 having a recirculation valve 40, and a recirculation line 42 extending between recirculation valve 40 and one of the plurality of coolant circulation ports 28 and 30. Thermostat assembly 38 may be operable to direct coolant to circulate through machine 12 and an additional heat exchange mechanism 44 such as an engine oil cooler, until the coolant has reached a certain temperature, at which point recirculation valve 40 may be adjusted to enable coolant to be conveyed through a supply line 43 to radiator tank 16.

Referring now to FIG. 2, there is shown a cooling system 110 according to another embodiment, and having similarities with the embodiment of FIG. 1 except with regard to placement of a valve mechanism 148 relative to other components of cooling system 110. Rather than a design such as that depicted in FIG. 1 where both valve mechanism 48 and radiator cap 46 are mounted at a top of radiator tank 16, in cooling system 110 radiator cap 146 is mounted at a top of radiator tank 116, and valve mechanism 148 is mounted slightly vertically lower than radiator cap 146 relative to a vertical axis 200. It will be appreciated that it is generally desirable to mount pressure relief and coolant return mechanisms as close as possible to the top of a radiator tank. In certain instances, however, such as where internal structures of the radiator tank present obstacles to forming bores through the tank wall, or the tank wall is itself too thin, alternative mounting configurations are desired such as that shown in FIG. 2. Referring back to FIG. 1, it can also be noted that in cooling system 10 coolant circulation port 30 is positioned vertically higher than coolant circulation port 28. Recovery bottle 34 includes a bottle inlet 35 positioned vertically lower than overflow port 26. In FIG. 1 overflow port 26 is positioned more or less at the same vertical location as tank access port 24, whereas in cooling system 110 an overflow port 126 is positioned vertically lower than a tank access port 124.

Valve mechanism 48 may further include a pressure relief valve 56 within valve body 50 and positioned fluidly between inlet 52 and outlet 54 and a coolant return valve 58 positioned fluidly between inlet 52 and outlet 54. Pressure relief valve 56 and coolant return valve 58 may each be pressure-operated, based upon a pressure difference between inlet 52 and outlet 54 in a manner further described herein. To this end, pressure relief valve 56 may include a first valve opening surface 62 and a first valve closing surface 66. Coolant return valve 58 may include a second valve opening surface 64 and a second valve closing surface 68. Each of pressure relief valve 56 and coolant return valve 58 may be positioned at least partially within a fluid space 82 defined by valve body 50 and structured to fluidly connect inlet 52 and outlet 54 depending upon the state of pressure relief valve 56 and coolant return valve 58.

Each of pressure relief valve 56 and coolant return valve 58 may be movable between an open position and a closed position, and may be biased towards the respective closed position. In an embodiment, valve mechanism 48 includes a first biaser 92 biasing pressure relief valve 56 towards the respective closed position, and a second biaser 94 biasing coolant return valve 58 towards the respective closed position. Each of first biaser 92 and second biaser 94 may include a biasing spring. First biaser 92 may be held in compression between pressure relief valve 56 and coolant return valve 58, and second biaser 94 may be held in compression between coolant return valve 58 and pressure relief valve 56.

It can be further noted from FIG. 3 that pressure relief valve 56 and coolant return valve 58 are reciprocal generally along a longitudinal axis 300 defined by valve body 50 and extending between a first axial end 78 wherein inlet 52 is formed and a second axial end 80 wherein outlet 54 is formed. Pressure relief valve 56 and coolant return valve 58 may further be structured such that pressure relief valve 56 is movable in a first opening direction within valve body 50 and coolant return valve 56 is movable in a second opening direction within valve body 50 that is opposite to the first opening direction. Pressure relief valve 56 may be nested with coolant return valve 58. In a practical implementation strategy, each of pressure relief valve 56 and coolant return valve 58 has a fixed angular orientation within valve body 50 about longitudinal axis 300. Pressure relief valve 56 may include a movable valve member 84 coupled with a sealing member 86, movable to contact a seat 88 formed by valve body 50. Valve member 84 may include a metallic piece whereas sealing member 86 may include a non-metallic piece attached to valve member 84 and having an annular shape. In a practical implementation strategy, a plurality of fluid ports 85 may be formed in valve member 84 enable fluid communication between cavity 82 and valve opening surface 64. In other embodiments different geometry altogether might be used, or a different arrangement of the respective valves. For example, a pressure relief valve and a coolant return valve need not be nested with one another and in other instances could be positioned in parallel, or in separate sections of a valve body or in separate valve bodies altogether. Those skilled in the art will contemplate various further alternatives.

It can also be seen from FIG. 3 that cap 46 fluidly seals tank access port 24. Tank access port 24 could be used for filling cooling system 10, or for other purposes. In a practical implementation strategy, cap 46 includes a solid cap having an unperforated metallic body 70 with a pressure side 72, and an ambient side 74, and a non-metallic sealing member 76 sandwiched between pressure side 72 and ambient side 74.

In the illustrated embodiment, each of the various ports formed in tank wall 18 extends by way of a bore between inner surface 22 and outer surface 20. In the case of overflow port 26 a portion of the bore through tank wall 18 may be threaded by way of a second set of threads 99 engaged with a first set of threads 98 formed on a connector 51 of valve body 50. It can be seen that connector 51 has a tapered shape such that the set of threads 98 forms a tapered profile, which tapered profile is complementary to a tapered profile formed by the set of threads 99. In the case of tapered threads a fluid seal between valve body 50 and radiator tank 16 can be accomplished by way of metal-to-metal wedging amongst the mating threads. It can further be seen from FIG. 3 that pressure relief valve 56 is in an open state such that a clearance 96 extends between valve body 50 and sealing member 86 as valve mechanism 48 might appear when open in response to a pressure drop from inlet 52 to outlet 54. Coolant return valve 58 is closed, resting against a seat 90 formed by valve member 84. In a normal, rest state or first state of valve mechanism 48, first valve opening surface 62 is exposed to a fluid pressure of inlet 52, such that pressure relief valve 56 opens in response to a pressure drop from inlet 52 to outlet 54, to convey coolant from radiator tank 16 to recover bottle 34. The pressure drop sufficient to open valve 56 might be about 5 PSI to about 20 PSI, corresponding to an internal pressure in radiator tank 18 of about 5 PSIG to about 20 PSIG. In the first state, second valve opening surface 64 may be exposed to a fluid pressure of outlet 54, such that coolant return valve 58 opens in response to a pressure drop from outlet 54 to inlet 52, to convey coolant from recovery bottle 34 to radiator tank 16. The pressure drop sufficient to open valve 58 might be about 5 PSI or less, potentially about 1 PSI. Valve mechanism 48 blocks fluid flow through overflow port 26 in the first state, and is adjustable to a second state to permit fluid flow through overflow port 26 by way of opening pressure relief valve 56 responsive to a pressure drop from inlet 52 to outlet 54 or to a third state to permit fluid flow through overflow port 26 by way of opening coolant return valve 58 in response to a pressure drop from outlet 54 to inlet 52. Pressure relief valve 56 may thus have a first valve opening pressure based at least in part upon a size of first valve opening surface 62 and a stiffness of first biaser 92, and coolant return valve 58 a second valve opening pressure based at least in part upon a size of the second valve opening surface 64 and a stiffness of second biaser 94. The first valve opening pressure may be greater than the second valve opening pressure.

Referring now to FIG. 4, there is shown a valve mechanism 248 including a valve body 250, and in a cooling system 210 according to another embodiment. Valve mechanism 256 is coupled with a radiator tank 216 and includes a pressure relief valve 56 and a coolant return valve 258 positioned fluidly between an inlet 252 and an outlet 254 formed in valve body 250, to control fluid flow through an overflow port 226. Valve mechanism 248 functions in a manner similar to valve mechanism 48 described above. In FIG. 4 valve mechanism 248 is shown as it might appear where coolant return valve 258 is in an open position and fluid flow is possible through a clearance 296 between coolant return valve 258 and pressure relief valve 256. It can also be seen that a connector 251 of valve body 250 has a structure different from connector 51 described in connection with valve mechanism 48. In particular, rather than tapered threads, connector 251 may be equipped with straight threads in a set 298 engaged with straight threads in a set 299 formed in radiator tank 216. An annular sealing element 253, such as an O-ring, is compressed and positioned axially between valve body 250 and radiator tank 216. Radiator tank 216 includes threads 299 extending circumferentially around overflow port 226 and mated with threads 298. A similar characterization of threads extending circumferentially around an overflow port can be made with regard to the embodiment of FIG. 3.

INDUSTRIAL APPLICABILITY

Referring to the drawings generally, but with particular reference to cooling system 10, during operating cooling system 10 coolant may be conveyed between radiator tank 16 and coolant circulation loop 32 to exchange heat with machine 12. The exchange of heat will tend to cause an increase in a temperature and a pressure of the coolant within cooling system 10. In response to the increase in pressure, pressure relief valve 56 in valve mechanism 48 is opened to enable venting of an excess volume of the coolant that is produced, in response to the increase in temperature, to recovery bottle 34. At a later time during operation, or potentially during or after shutting down machine 12, the temperature and the pressure of the coolant can decrease, causing coolant return valve 58 in valve mechanism 48 to open in response to the decrease in pressure. It has been observed that the cooling and contracting of coolant within radiator tank 16 can cause a vacuum to develop within space 60. Coolant is returned by way of the opening of coolant return valve 58 to radiator tank 16. During conveying coolant into and out of radiator tank 16 in the manner described, leakage of coolant and air through tank access port 24 can be inhibited by way of cap 46.

It has been observed that certain earlier radiator cap designs included structure for enabling pivoting of the cap body relative to components of the radiator cap including a pressure relief valve and/or a coolant return valve, for instance which necessitated a breach in the otherwise fluidly sealed body of the cap. Those skilled in the art will appreciate the thermally dynamic conditions under which machine cooling systems must operate. Components expand and contract in response to changes in temperature, experience thermal fatigue, and can be corroded or otherwise degraded in performance by the relatively harsh conditions. The pivot pin or other structure in a radiator cap and the associated breach in the otherwise fluidly sealed barrier had a tendency in response to the changes in temperature and pressure, to form a leak path enabling air to be drawn into the coolant system. The present disclosure provides for separating pressure relief and coolant return functions between the radiator cap and other apparatus, eliminating or at least reducing the possibility of air entering the system and causing a host of known problems.

The present description is for illustrative purposes only, and should not be construed to narrow the breadth of the present disclosure in any way. Thus, those skilled in the art will appreciate that various modifications might be made to the presently disclosed embodiments without departing from the full and fair scope and spirit of the present disclosure. Other aspects, features and advantages will be apparent upon an examination of the attached drawings and appended claims. 

1. A cooling system for a machine comprising: a radiator assembly including a radiator tank having formed therein a tank access port, an overflow port, and a plurality of coolant circulation ports, for connecting with a coolant circulation loop; a recovery bottle; a vent line fluidly connected with the recovery bottle; the radiator assembly further including a cap coupled with the radiator tank to seal the tank access port, and a valve mechanism; the valve mechanism including a valve body attached to the radiator tank and having formed therein an inlet fluidly connected with the overflow port, and an outlet fluidly connected with the recovery bottle by way of the vent line; the valve mechanism further including a pressure relief valve positioned fluidly between the inlet and the outlet and having a first valve opening surface, and a coolant return valve positioned fluidly between the inlet and the outlet and having a second valve opening surface; the first valve opening surface being exposed to a fluid pressure of the inlet, such that the pressure relief valve opens in response to a pressure drop from the inlet to the outlet, to convey coolant from the radiator tank to the recovery bottle; the second valve opening surface being exposed to a fluid pressure of the outlet, such that the coolant return valve opens in response to a pressure drop from the outlet to the inlet, to convey coolant from the recovery bottle to the radiator tank; and the valve mechanism further including a first biaser contacting the pressure relief valve and holding the pressure relief valve in a closed position, and a second biaser contacting the coolant return valve and holding the coolant return valve in a closed position.
 2. The system of claim 1 further comprising a thermostat assembly including a recirculation valve, and a recirculation line extending between the recirculation valve and one of the plurality of coolant circulation ports.
 3. The system of claim 1 wherein the radiator tank defines a vertical axis, and wherein a first one of the plurality of coolant circulation ports is positioned vertically higher than a second one of the plurality of coolant circulation ports, and the recovery bottle includes a bottle inlet positioned vertically lower than the overflow port.
 4. The system of claim 3 wherein the overflow port is positioned vertically lower than the tank access port.
 5. The system of claim 1 wherein the cap includes a solid cap having an unperforated metallic body with a pressure side, and an ambient side, and a non-metallic sealing member sandwiched between the pressure side and the radiator tank.
 6. (canceled)
 7. The system of claim 1 wherein the valve body defines a longitudinal axis, and each of the pressure relief valve and the coolant return valve has a fixed angular orientation about the longitudinal axis.
 8. The system of claim 7 wherein the pressure relief valve has a first valve opening pressure based at least in part upon a size of the first valve opening surface and a stiffness of the first biaser, and the coolant return valve has a second valve opening pressure based at least in part upon a size of the second valve opening surface and a stiffness of the second biaser, and wherein the first valve opening pressure is greater than the second valve opening pressure.
 9. The system of claim 8 wherein the pressure relief valve is movable in a first opening direction within the valve body and the coolant return valve is movable in a second opening direction within the valve body that is opposite to the first opening direction.
 10. A radiator assembly comprising: a radiator tank including an inner surface defining an internal fluid space, and an outer surface, and having formed therein a plurality of coolant circulation ports, a tank access port, and an overflow port; a cap coupled with the radiator tank at the tank access port and blocking fluid flow through the tank access port; a vent line; a valve mechanism coupled with the radiator tank at the overflow port, and including a valve body having formed therein an inlet fluidly connected with the overflow port, and an outlet fluidly connected to the vent line to fluidly connect with a recovery bottle; the valve mechanism further including a pressure relief valve having a first valve opening surface, and a coolant return valve having a second valve opening surface; the valve mechanism being in a first state where the first valve opening surface is exposed to a fluid pressure of the inlet, the second valve opening surface is exposed to a fluid pressure of the outlet and the valve mechanism inhibits fluid flow through the overflow port; and the valve mechanism being adjustable to a second state to permit fluid flow through the overflow port by way of opening the pressure relief valve responsive to a pressure drop from the inlet to the outlet or to a third state to permit fluid flow through the overflow port by way of opening the coolant return valve in response to a pressure drop from the outlet to the inlet; the radiator tank defining a vertical axis, and wherein a first one of the plurality of coolant circulation ports is positioned vertically higher than a second one of the plurality of coolant circulation ports; and the overflow port being positioned vertically lower than the tank access port, and wherein the cap is attached to a top of the radiator tank and the valve body is attached to a side of the radiator tank such that the valve mechanism conveys coolant between the radiator tank and the vent line at the location that is vertically lower than the tank access port.
 11. The assembly of claim 10 wherein the pressure relief valve is movable in a first opening direction within the valve body and the coolant return valve is movable in a second opening direction within the valve body that is opposite to the first opening direction.
 12. The assembly of claim 11 wherein the pressure relief valve is nested with the coolant return valve.
 13. The assembly of claim 12 further comprising a first biaser biasing the pressure relief valve toward a closed position, and a second biaser biasing the coolant return valve toward a closed position.
 14. The assembly of claim 13 wherein the first biaser is held in compression between the pressure relief valve and the valve body, and the second biaser is held in compression between the coolant return valve and the pressure relief valve.
 15. The assembly of claim 10 wherein the valve body defines a longitudinal axis extending between a first axial end and a second axial end, and wherein the inlet is formed in the first axial end and the outlet is formed in the second axial end.
 16. The assembly of claim 15 wherein the valve body includes a connector located at the first axial end and including a first set of threads, and the radiator tank includes a second set of threads extending circumferentially around the overflow port and mated with the first set of threads, and wherein the valve body further includes a second connector located at the second axial end and having the outlet formed therein.
 17. The assembly of claim 16 wherein the first set of threads include external threads, and wherein the connector has a tapered shape such that the first set of threads forms a tapered profile.
 18. (canceled)
 19. The assembly of claim 10 wherein the cap includes a solid cap having an unperforated metallic body with a pressure side, and an ambient side, and a non-metallic sealing member sandwiched between the pressure side and the radiator tank.
 20. A method of operating a cooling system for a machine comprising: conveying a coolant between a radiator and a coolant circulation loop structured to exchange heat with a machine; increasing a temperature and a pressure of the coolant within the cooling system by way of the exchange of heat; opening a pressure relief valve in a valve mechanism attached to a side of the radiator at an overflow port in response to the increase in pressure; venting an excess volume of the coolant produced in response to the increase in temperature to a recovery bottle by way of the pressure relief valve; decreasing the temperature and the pressure of the coolant such that a volume of the coolant is reduced; opening a coolant return valve in the valve mechanism in response to the decrease in pressure; returning coolant to the radiator by way of the coolant return valve; and inhibiting leakage of coolant and air through a tank access port during the venting of the excess volume of coolant and the returning of the coolant to the radiator by way of a solid cap attached to a top of the radiator and fluidly sealing the tank access port. 